Exhibiting diffraction-photographs.



F. E. IVES.

EXHIBITING DIPFRAGTION PHOTOGRAPHS. APPLICATION FILED 00130, 1905.

PATENTED JAN. 1, 1907.

UNITED PATENT OFFICE.

EXHIBITING DIFF Specification of Letters Patent.

RACTlON-PHOTOGRAPHS.

Patented Jan. 1, 1907.

Application filed October 30, 1905. Serial No. 285,162.

To all whom/it 7211a concern:

. Be it known that I,- Fnnnnnro EUGENE IVES, a citizen of the United States, residing in Woodelifl'e-on-Hudson, New Jersey, have invented certain Improvements in Exhibiting Diffraction-Photographs, of which the following is a specification.

Diffraction-color photographs consist of three superposed or mixed images printed in fine diffraction-lines in clear gelatin or albumen to represent the three primary colors and their combinations. The spacing of the diffraction-lines is different for the different color elementssay two thousand lines to the inch for the red, two thousand six hundred for the green, and two thousand nine hundred for the blue. Viewed byperfectly diffused transmitted light these photographs are quite invisible, but can be made visible with 7 order to obtain successful results.

an approximation to the natural colors by. viewing them in'a special device with a point or line of light a portion of which is dis persed and laterally displaced by the diffracting-lines of the photograph and focused upon the eye by means of a suitable lens. The source of light is usually a gas or lamp flame turned edgewise to the axis of the lens and ata distance of several feet from it. One objection to this device is that the color of a gas-flame is not suitable for obtaining the best results and another is'that some considerable skill is required to make the necessary adjustments, and they are lost again by a very slight disturbance of the instrument.

Some of the diffraction-photographs also require to be viewed by first-order spectra and others by second-order spectra in order to' give the best results, and the necessary changes of adjustment are troublesome and likely to be very imperfectly performed by any but skilful experts.

The object of my invention is to so exhibit a diifractioncolor photograph that satisfactory illumination can be obtained by diffused daylight, and incidentally to permit fixed adjustment and convenient disposition of the various instrumentalities necessary to such exhibition, so that no skill is requiredin In the accompanying drawings, Figure 1 i a diagrammatic representation of means heretofore employed for exhibiting a diffractionecolor photograph. "/Fig. 2 is a longitudinal sectional view of a device for exhibiting such photographs in accordance with my invention, and Fig. 3 is a plan view of the same.

In Fig. 1 of the drawings, (1 represents a source of light, I) a difl'raction-photograph, c a focusing-lens, m a position where the lens 0 appears filled with white light, and w a position where the graduated spectra of one order are suitably superposed and focused upon the eyered spectrum rays from one grating,photograph-image, green from another, and blue from the third-so that there appears to be'a color photograph at b. At y spectra of the second order may be similarly utilized. On the other side of the axis are similar s ectra, either of which may be util ized. I the axis of the instrument is suitably dis laced with respect to the position of and the superposed spectra at w, or the White at y and the superposed second-order spectra at m. A larger or closer source of light may be used by placing it behind a slit in an opaque screen, such as shown at a, and inserting another lens-sueh, for instance, as shown at c-to parallelize the rays, and this method of procedure wouldeven admit of the use of diffused daylight but for the fact that where spectra of only one order are utilized, as in the device described, diffused daylight does not give sufficiently strong illumination to be satisfactory.

.I overcome the objections to the present procedure, first, 'by using multiple slits or sources of light so disposed as to utilize two or more of the spectra from each diffractionimage, thus doubling. or even under certain conditions quadrupling the illumination; secondly, by attaching the slitted diaphragm to the viewing device so that the adjustments are fixed, and, thirdly, by making a turn in the axis of the instrument with a base-line so disposed as to make the angles of illumination and vision more convenient and satisfactory.

In Fig. 2 of the drawings, A and B represent, respectively, the base and easing of the instrument hinged together at C. D is a slit nearthe eye-point. E and F are lenses. G is a mirror, and the line H H is the normal optical axis. J represents grooves for receiving the diffraction-photograph slides, and K K K K are slits 1n an opaque screen L attached to one end of the case. M M are lines showing the form of a cone of normal axial rays on both sides of the lenses F and E,

a, the W lite light may be made to focus at w which are separated not only to permit of the insertion of the diflraction-photograph, butabove sets of spectra-namely, first and second in order to permit of changing its position to suit eyes having either long, normal, or short sight, and this separation may possibly be reduced to some advantage in other respects. From each slit there are therefore three spectraone by the two thousand line ruling of the diffraction-photograph, one by the two thousand six hundred line diffractionruling, and the third by the two thousand nine hundred line difi'raction ruling, and the triple spectra thus produced are so su erposed that at one point the mixture is w ite to the eye.

In the absence of a diffraction-photograph between the lenses E and F lig it entering the slit D would normally be focused upon the inside of the opaque diaphragm L at its center, and light passing in the other direction through the slits K K K K would be thrown or below the slit D, vand so lost to vis- 1011'. When, however, a diffraction photograph is inserted between the lensesE F, the difiraction-lines in the hotograph, dis ersing and deflecting light v om I), would t ow superposed spectra on all of the slits K K K K, and, conversely, all of the first and second order spectra obtained from li ht coming through the slits K K K K won (1 be superposed at D. The diffraction-photo aph would therefore be seen by the llght 0 four order spectraon each side and the'illumination would begr'eatly increased over that which could be. obtained by utilizin only one set of spectra. If the slits K Kielonging to the second-order spectra be made twice as wide as those belonging to the first-order fipectra, which is permissible, because the lspersion is twice as great, the illumination mav possibly be quadrupled as compared with t spectra. This arrangement possesses other advantages which may be less obvious, but are of considerable practical importance. For example, some of the diffractionhotographs throw more light into thesecon order spectra than into the first, and vice versa', and sometimes the diffraction-lines belonging ,to

one of the superposed or mixed images act.

differently in this respect from those belonging to the others, an some times one side-or portion of the difi'raction photogra h acts diflerently in this respect from the ot er side at obtained with one set of first-order or portion. The mixing of the several spectra corrects errors thus introduced into single spectrum images and makes the reproductrons not only more brilliant, but more correct and harmonious. ,In addition to the advantages already enumerated the use of slits horizontally disposed and of appropriate length or appropriately' spacedt ogether with diifraction-photographs having the difi'ractionlines horizontally disposed permits the ima es to be viewed Wlth both eyes at once, an I believe that binocular vision with the eyes on opposite sides of the normal axis of a diffractionphotograph-viewing device is also a new and valuable improvement.

The bend 1n the axis of the instrument provides for the convenient use of a window or other source of light, as well as for convenient viewing of the images.

, My im(proved viewing instrument, while to operate "most successfully in" calculate diffused daylight, may be very satisfactorily used with artificial li ht by placing it near the'source of liht wit a ground glassover the diaphragm and the color of the light may be modified and improved by adding also a pale cobalt-blue glass or other modifying screen.-

do not hereinclaim the instrument shown and described, as this forms the subject of a se' arate a lication filed b 'meon the 21st P Pg Y day of Marc 1906, Serial No. 307,215.

Having thus described my invention, claim and desire to secure byLetters Patent- 1. The mode herein described of exhibiting a diffraction-color photograph, said mode consisting in superposlng two or more of the triple s ectra at the view-point.

2. T e modeherein described of exhibiting a difiraction-color photograph, said mode consisting in .superpos ng right and left side spectra at the-v1ew-po1nt.

3. The mode herein described of exlnblting a difiraction color photograph, said mode consisting in sulperposing spectra of two or more orders att ewew-point. g I

In testimony whereof I havetsigned my name to this specification in the presence of two subscribin witnesses;

FR DERIC EUGENE IVES.

' Witnesses:

. WM. E. Snore;

Jos. H. KLEIN. 

